Coolant issues, possible head gasket problem

Ive got a 99 bmw 740iL, new cat converters, oxy sensors, brakes, water pump, and thermostat.
The Check Coolant warning comes on when i try to drive. I filled it
up, and in two days it said to check again-there was no coolant at all in the tank. So i filled it up again and the next day i saw lots of antifreeze on my garage floor.
There are no visible leaks, ive taken the car to a trusty mechanic and the are no obvious drips when he put it up on the lift. Also, when i do drive with the car it doesnt go into the "red zone"(it doesnt overheat). After driving it for about 5-10 min and letting it cool down, i opened the coolant cap and there was a gurgling noise and coolant spilled out onto the floor. The mechanic has told me that its a gasket problem(i think head) and that he needs to send out engine heads to be checked and change the gaskets. I was told itd be about $2000(U.S.) to fix it. Ive taken it for a 2nd opinion to a heat/cool system specialist, they havent finished diagnosing it, but when we discussed it they said it possibly could be the thermostat.
Ive seen gasket parts on the internet for 50+ bucks...why am i being told that its a $2000 fix? Id like to know what problems have similar symptoms and if it might be something other than what ive been told by that one mechanic so far. I know its a long post, so thanks in advance.
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It is a lot of work to get at those cheap parts. It is a lot of work to check those heads Labor costs are quite high. Besides that this is a BMW 740... Did anybody run a pressure check on the cooling system? My old 1954 Ford V8 had a problem similar to this; it turned out to be a cracked head. But your problem might be something else. Jim
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Nope, no pressure checks on the cooling system, i'll tell them to try it. Labor is okay, ive got a good mechanic that is a friend, i was thinking the heads was what costed so much...no way to avoid that i suppose. I don't get what ya mean by getting those cheap parts, which parts, and how much do they cost? ive only seen 50 buck parts, which is very cheap to me($2000 is alot to fix it) Thanks alot by the way
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Radiators on these cars are fragile. I'd also try a new thermostat gasket.
Any mechanic who wants to open up a head before pressure testing the system should be regard with caution.
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Email: snipped-for-privacy@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland
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snipped-for-privacy@aol.com wrote:

Are there two heads on this engine? I guess you need to find out which is bad. In my experience garages always quote double for a head gasket change because it's not run of the mill servicing. They might also need special tools to keep the cam timeing etc in place but I'm not sure.
What lead up to the waterpump needing to be replaced anyway? Did the car overheat before?
If you've got coolant on your garage floor then you should be able to find out where it's coming from. Coolant is under pressure when it's hot and if you release that pressure it can make it bubble over. You might also get localised boiling if there's an air trap somewhere.
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The gaskets are the cheap parts. Removing and replacing the heads are where most of the money goes. The mechanic really really should do a pressure check. Otherwise, he may be chasing a false lead. Jim
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Jim, i have a 94 740il and mine was doing the same thing....put paper under the front half of the car and them traced the leak back ....turned out it was a formed hose coming from the bottom of the coolant tank on the drivers side...hope its what's wrong with yours...easy and a lot less expensive to fix...
cw

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